Automatic test pattern generation (ATPG) is used to identify test sequences which can be applied to circuits in order to determine whether they behave correctly. In ATPG, test patterns are mathematically generated and used to test semiconductor devices after manufacture. Test patterns may also be used to assist in the determination of the causes of defects.
The power consumption of semiconductor chips while their circuits are in testing modes, such as those generated using automatic test pattern generation, may be much larger than their power consumption during functioning modes. The increased power requirements may be in the order of three to thirty times greater when in testing modes. This difference in power requirements may result in false failures during test, damage to the circuitry occurring during testing or future reliability problems due to high junction temperatures.